4 Answers
4

I heard on a R' Hershel Shachter shiur @yutorah that the older practice was in fact to have one rabbi (often the officiating one) to recite them all. Just as a haftorah or the like has multiple blessings, recited by one person.

In order to spread the honors, today people will often give one (or more) blessings per person. If that works for you, fine; if you want one person to do them all, that's fine too. (But if your cousin's father-in-law's chiropractor's best friend gets upset that he didn't get one, please don't blame me!)

Rabbi Yoel Teitelbaum of Satmar, reacting to the recent divvy-'em-up trend, remarked that pretty soon, they'll have one person say BA and another person say RUCH!

At my wedding, the rav / mesader kiddushin did all the brachot. Practical reasons:

We avoided "family politics". Inevitably, if we would have given to some people, others would have really been insulted. Funny how "childish" people become at your simcha, even from your best friends.

The rav was also a noted chazzan, who was a very close member of both my kallah and my side of the family. At the end, the majority of the attendants enjoyed hearing his voice.

We were running on a very strict timeline. When you deal with caterers and bands, 5 minutes overtime = 1 hour of overtime that you have to pay, and we weren't going to do any overtime. Calling extra people would have taken an extra 5 minutes.

That last item may sound incredulous, but, this was really the case. I'm not stating that this is a concern for most people, but, it very well might be.

Also, while most people are glad to attend your wedding (some, interestingly, are not, but come, anyway - I can't figure that out), almost no one likes a chuppah that's longer than necessary. People become impatient after a while. I can't say why, nor do I find such attitude correct (really? 5 minutes longer makes people impatient??), but that's what it often is.

I don't know why someone downvoted. He claims that a certain rabbi said it was ok to say together. That's an answer. It's not particularly useful since I don't know who that rabbi is, but it's not downvote-worthy.
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Double AA♦Jan 13 at 0:00

@DoubleAA, the downvote link's tooltip is "This answer is not useful". This answer is not useful. I was the downvoter.
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msh210♦Jan 13 at 0:06

@msh210 It tells you that one rabbi once somewhere thought it was ok. That's marginally useful. It certainly doesn't add anything over the other answers.
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Double AA♦Jan 13 at 0:10